Coil construction and method of making the same



April 12, 1955 J. GUZZO ETAL 2,706,280

COIL CONSTRUCTION AND METHOD OF MAKING THE SAME Filed Dec. 30. 1950 3Sheets-Sheet l LIZENTOIZZ. #82 5J1: mm L April 12, 1955 J. GUZZO ETALCOIL CONSTRUCTION AND METHOD OF MAKING THE SAME 3 Sheets-Sheet 2lNVfiNl/jii: 'GQML in 1 H y 1 r m lmm Filed Dec. 30, 1950 April 12, 1955J. GUZZO ETAL COIL CONSTRUCTION AND METHOD OF MAKING THE SAME 3Sheets-Sheet 3 Filed Dec. 30. 1950 Mai United States Patent COILCONSTRUCTION AND METHOD OF MAKING THE SAME Joseph Guzzo, Chicago, andAmi Helgason, Wilmette, Ill., assignors to Essex Wire Corporation, CookCounty, 11]., a corporation of Michigan Application December 30, 1950,Serial No. 203,726

4 Claims. (Cl. 336-182) This invention relates to a coil constructionand method of making the same and more particularly to a constructionembodying a plurality of pancake or pie windings and method of makingthe same. In certain types of transformers, it is necessary to dividethe primary or secondary, or both, into a number of separate windings orunits. This expedient becomes necessary when the distributed capacitanceof coils is to be reduced or is necessary for other reasons. It hasalways been the practice to make each pancake winding in a conventionalmanner, each such winding being physically and electrically separatefrom the other windings. Thereafter, a number of such windings aredisposed in side by side relation on a magnetic core and suitableconnections made between them as desired.

It is desirable to integrate a number of such pancake windings for onecoil into one unitary physical structure while retaining the electricalidentity of each winding distinct from the other windings in a coil.With such an integral construction, the same insulating material is moreeffective. A coil consisting of a number of pie windings may be handledeasier and more economically. Furthermore, a unitary coil consisting ofa predetermined number of pie windings is desirable since the separatepie winding cannot be misplaced or reversed. In addition, the unitaryphysical structure of the coil reduces the mechanical vibration betweenwindings occurring at audio-frequencies when currents of sufiicientmagnitude pass through the windings.

The method of making the new coil as hereinafter described results inmanufacturing economies in addition to providing an improved product.The new method insures uniformity of turns and layers in all piewindings and makes accidental diiferences impossible.

The invention here relates to a coil and a method of making such a coilwherein the insulating portion of all of the windings may be integraland common while the conducting portions of the windings areelectrically separate and distinct.

The invention in general provides for Winding in tandem any desirednumber of pie windings for any desired number of coils. As used herein,a coil will be considered as made up of a number of electricallyseparate but physically integral pie windings. The inventionmakes itpossible to provide such windings without in any manner limiting theavailability of any parts of the pie windings, or connection to otherparts of other pie windings, or to outside circuits.

It is old to wind a number of windings in tandem and thereafter saw thewindings so that each such winding is physically separate from otherwindings. In such case, no difficulty is experienced in locating theinside and intermediate leads of a winding for connection to otherwindings or to outside circuits. As a rule, such leads of a winding arelocated simply by probing at the sides of the winding and pulling thewire out for use.

Where a number of pancake or pie windings are physically intact althoughelectrically isolated to form a coil, provision for making electricalconnection to the inside or intermediate parts of all of the windingsmust be provided. One end winding of such an integral structurecontaining a number of pie windings may have the inner end andintermediate terminals or leads located in conventional manner byprobing at the sides. Assuming that every pie winding is startedsimilarly from one side of each winding, it is clear that only one endwinding of a coil may thus be handled. The same procedure is "iceinapplicable to the remaining pie windings since the inner end andintermediate ends will be inaccessible.

In accordance with this invention, a construction is provided and amethod of winding is provided which eliminates the above disadvantages.A new coil embodying the present invention makes it possible to have asmany pie windings as may be desired, all connected together physicallyas one integral construction with readily available connection for theinterior parts of every pancake winding forming the entire coil.

In order that the invention may be understood, it will now be explainedin connection with the drawings wherem:

Figure 1 shows a perspective view of a transformer having coilsembodying two modified forms of the inventron;

Figure 2 is a perspective view showing the beginning of winding of onecoil embodying the present invention;

Figure 3 is an end view of a finished coil embodying one form of thepresent invention;

Figure 4 is a diagrammatic view of part of a winding machineillustrating the beginning of winding of a number of coils embodying oneform of the invention;

Figure 5 is a transverse sectional view of a completed coil embodyingone form of the invention;

Figure 6 is a diagrammatic view of a winding machine illustrating thebeginning of the winding operation for coils embodying a modified formof the invention;

Figure 7 is an end view partly in section illustrating the completedcoil embodying a modified form of the invention;

Figure 8 is an enlarged detail of the coil of Figure 7;

Figure 9 is an end view similar to Figure 7 but showing a furthermodification.

Referring first to Figure 1, there is shown transformer 10 havingconventional laminated core 11 and coils 12 and 13. Coils 12 and 13 mayform the primary and secondary windings respectively of the transformer,it being immaterial which is the primary and which is the secondary.Both coils are shown as embodying two modifications of the invention forthe sake of illustrating these two modifications. It is, of course,possible to have only one coil embodying the invention and have theother coil of conventional construction.

Coil 12 may be made up of any number of pancake windings and as shownhere, consists of four pancake windings 15 to 18 inclusive. Similarly,coil 13 may be made up of any number of pancake windings and consists ofwindings 20 to 23 inclusive.

It is understood, that transformer 10 is conventional as far as the coreis concerned and the manner in which the coils are assembled upon thecore.

Referring now to Figures 2 to 5 inclusive, a detailed description of oneform of the invention, together with a method for winding a coilembodying one form of the invention, will follow.

This invention makes it possible to follow closely conventional coilwinding practice. Thus a number of coils are wound by first startingwith form 25. This form consists generally of a paper or cardboard tube,usually of generally rectangular cross section. Thus the completed coilcan be slipped over the correspondingly-shaped magnetic core.

Form 25 is long enough so that a substantial number of separate coilscan be wound in tandem. Form 25 is slipped over mandrel 26 of a windingmachine, mandrel 26 having its ends supported in suitable bearings. Themandrel is driven by suitable means, this being conventional in the artand not being described or shown. As shown in Figure 4, form 25 is longenough to accommodate four sets of complete coils in tandem. This numberis merely exemplary and it is understood that the number of coils woundin tandem may be less than or greater than the four shown. It is alsounderstood that each coil as shown on the drawings consists of fourpancake windings. The number of pancake windings on the respective coilsmay be the same or may be different and this may be less than or greaterthan shown in the drawing.

Referring specifically to Figure 4, coils 27 to 30 inclusive are shownas being formed. Thus specifically referring to coil 27 as an example,this is made up of four pancake windings 31 to 34 inclusive. The dottedlines indicate the dividing line between the opposed sides of theadjacent pancake windings, these sides being formed by the end planes ofthe end turns of the winding. In practice, paper between superposedlayers of wire would extend beyond these planes. Hence, the dotted linesmerely indicate the limits for the wire turns for each pancake winding.

Between coils 27 and 28 is dotted line 36 which forms a dividing linebetween adjacent coils along which cutting occurs. Thus after thewindings have been formed and adjacent coils are to be sawed apart, itis understood that the cutting will take place along line 36 and similarlines between adjacent coil ends. The procedure with respect to theindividual pancake windings for coil 27 is the same as for the remainingcoils so that the description will proceed in detail for coil 27 exceptwhere other coils are specifically referred to.

Pancake windings 31 to 34 inclusive, forming coil 27, are themselvesformed by winding wires 31a to 34a inclusive. These wires pass throughsuitable guide rolls and tensioning means from individual spools, allthis being generally known in the winding machine art and requiring nodetailed description. Wire 31a and the corresponding wire in theremaining coils 28 to 30 inclusive, will be at the end of each coilafter the various coils have been sawed or cut apart.

Assuming that the winding is initially from left to rightthis', ofcourse, may be reversedwire 31a may be handled in a conventional manner.Thus wire 31a may be turned around form 25 several times to provide alength of lead. If the wire is too fine, the end of wire 31a may besoldered to a heavier lead wire and this lead wire may be twisted aroundform 25 as desired. Thereafter, a sheet of insulating paper may bestarted around the entire length of form 25. It is understood that thisinsulation sheet may be outside of the few initial turns of wire 31a andthe corresponding wires at the left end of each of the remaining coils.

However, wire 31a may be handled in a manner similar to wire 32a.

Disposed at any desired side of form 25 are elongated conducting strips31b and 321). These conducting strips are preferably flat but may haveany shape and extend the full length of form 25. The thickness and widthof each conducting strip will depend upon the size of the pancakewinding, the amount of current to be carried, the gauge of wire to besoldered later to the conductor strips for connection purposes andvarious other factors. In general, however, conducting strips 31b and3211 may be of copper or brass and should be heavy enough so thatsoldering is possible. Wires 31a and 32a and the corresponding wires inremaining coils 28 to 30 inclusive are soldered to their respectivestrips.

In order to maintain the conducting strips in position temporarily,adhesive strips 31c and 32c may be disposed over the conducting stripsand extend beyond the sides of the conducting strips so as to contactthe insulating surface beneath them. Thus strips 310 and 320 willfunction as insulators for the top surfaces of the conducting strips andat the same time anchor the same on the form or whatever is over theform.

Instead of strips 310 and 320, tabs of adhesive paper may be disposed atspaced intervals to anchor the conducting strips to the form or otherfastening means may be used. It is possible to terminate the conductingstrips at the wires for coil 30 and not extend the conducting strips tothe very end of this coil. It is preferred, however, to have theconducting strips extend the full length of all the coils in order thatthe various wire layers may be wound in a uniform fashion. Furthermore,the capacitance between this strip and the remaining windings for eachcoil will be uniform in all the coils and the strips will be equallyaccessible at the two ends of each coil.

In order that the wires to be soldered to the conducting strips belocated promptly on such strips, it is possible to have each conductingstrip and its adhesive retainer prepared ahead of time with the tapehaving a suitable slot at the proper point on the conducting strip.

Pancake winding 33 is handled in a similar fashion by providingconducting strip 33b extending the full length of form 25 but along adifferent side of the form. This side may conveniently be the sidefollowing as the form is rotated for normal winding. For convenience,strip 33b is supplied with adhesive tape 33c and this tape is slotted orapertured at a suitable point as shown to line up the point forconnection to wire 33a.

Pancake winding 34 is similarly handled by providing conducting strip34b together with its tape 340 on still another side of the form. Wire34a is soldered to a suitable spot upon strip 34b, this spot beingadvantageously indicated by a notch in the conducting strip or a notchin the adhesive tape or both. The remaining wires for the remainingcoils are similarly handled.

After the various conducting strips are properly anchored, one or morelayers of sheet insulation 38 of paper or the like may be wound over theform by rotating the same as during normal winding, the various wiresbeing fed out over the paper. Thereafter, normal winding of the variouscoils proceeds. As will be readily understood, even during the provisionof one or more turns of sheet insulation, all the Wires are fed outsimultaneously so that every winding of every coil has the same numberof turns.

As winding proceeds, it is clear that any one or more pancake windingsof any one or more of the complete coils can be provided withintermediate conductor strips as desired. The outer terminals for thewindings may be handled in a conventional manner.

The conductor strips for the length of all the coils may generally bethe same length as all the coils in tandem or may be somewhat longer sothat the starting end of the left-hand coil in this particular instancehas the conducting strips projecting beyond the sides of the windingsand paper or coil proper. It will be apparent that the conductor stripswill be flush with the sides of the coils after they are sawed apart.Since the ends of the windings as distinguished from the paper will bebeyond the paper edge, it will be possible to spread the edges of thepaper to expose the raw end of the conducting strips and solder a leadwire thereto. Figure 1 shows leads on the conducting strips. If desired,the metal connector strips may have suitable apertures near the paperedges so that a lead may be inserted therein and be anchored securely.

As illustrated in Figures 1 to 5 inclusive, one conductor strip isdisposed on each side of the coil except two strips for wires 31 and 32in coil 27 and the corresponding wires for the remaining coils. Theseconductor strips may be as wide and as heavy as may be desired. In casea coil is large enough to accommodate a number of conductor strips inside by side relation along the same part of the coil, it may be simplerto wind such coils. Thus for example, as shown in Figure 6, coils 50 to53 are being wound in tandem. Coil 50, as an example, consists ofpancake windings 57, 58, 59 and 60 wound from correspondingly numberedwires with subscript a. Conductor strips 58b, 59b and 60b are disposedin spaced parallel relation along one side of the form upon which allcoils are to be wound. As shown here, end wire 57a is temporarilycemented at 57d on form 25 or may be wound a few times on the form priorto the application of the conductor strips or may be wound after theapplication of the conductor strips. It is understood that wirescorresponding to 57 in the remaining coils will be similarly handled.

In Figures 6 to 8 inclusive, the conductor strips, to which wires 58a,59a and 60a are respectively connected, are disposed on one side of thecoil form.

Preferably one or more sheets of insulation are provided betweenadjacent wire layers. Each of the conductor strips is provided with theadhesive tape as shown so that the conductor strips are anchored. As isshown, the wires are soldered to the conductor strips at proper pointson the windings. When every winding for every coil has thus been takencare of, normal winding is initiated and all the coils are accordinglywound in tandem. The treatment for the windings otherwise may be thesame as for the windings shown in the previously described figures.

Referring to Figure 9, it is possible to provide conducting strip 57bwith its adhesive cover strip 57c for wire 57a and the correspondingwire at the left end of coils 51, 52 and 53. Hence, every interior wireend will have its own conductor strip.

Conducting strips may be provided for the outer winding terminals, ifdesired. Other modifications will occur to those skilled in the art.

What is claimed is:

1. A coil construction for transformers or the like comprising a formextending the entire length of said coil, a plurality of windings intandem on said form, each winding having an inner and outer end andhaving superposed wire layers separated by sheet insulation, the sheetinsulation extending continuously for the length of the coil but thewire layers extending only for the length of the winding in which thelayers are disposed, the corresponding ends of the windings where theinner ends of the windings lie constituting the starting ends of thewindings, the coil as a whole having a starting end for one winding atone end of the coil, said coil having another winding at the other endof the coil, a conducting member for at least each of all windings otherthan the one winding, each con ducting member being straight and lyinglengthwise of the form for the full coil length and being disposedbetween the outside of the form and the innermost layer of each winding,the inner end of a winding being connected to the correspondingconducting member, the entire coil having accessible at the two endsthereof lead connections to otherwise inaccessible inner ends of theother windings and any additional windings which may lie between the oneand other windings, and connections for the outer ends of all windings.

2. As an article of manufacture, a plurality of coils joined end to end,each coil having the construction according to claim 1, the form, sheetinsulation and conducting members extending throughout the length of theplurality of coils and forming the joining means between the adjacentcoil ends.

3. The construction according to claim 1 wherein at least one additionalconducting member is provided, said additional member lying betweenadjacent wire layers where an intermediate winding tap is to be providedand extending the full coil length, the wire for the particular windingto be tapped being connected to said additional member.

4. The method of tandem winding a number of coils simultaneously, eachcoil itself consisting of a number of tandem windings, said methodcomprising providing a winding form of suitable length, laying on saidform lengthwise thereof for the full length thereof a number of straightconducting members, there being one conducting member for the inner endsof corresponding windings in the coils, connecting the correspondingstarting ends of wires to said members so that one conducting member isconnected to the starting ends of corresponding windings in the coils,tandem winding the wires to form the coil windings, separating adjacentwire layers by sheet insulation which extends for the length of saidform and continuing the winding operation until the outer ends of thewindings are reached.

References Cited in the file of this patent UNITED STATES PATENTS644,311 Anderson Feb. 27, 1900 649,086 Varley May 8, 1900 865,907 JodreySept. 10, 1907 1,713,941 Adams et a1 May 21, 1929 1,968,600 DriftmeyerJuly 31, 1934

